Answer:
If a nuclear reaction takes place without moderating material, the reaction will proceed at an uncontrolled and potentially explosive rate.
Step-by-step explanation:
Moderating materials, such as substances that contain light atomic nuclei like water or graphite, are used in nuclear reactors to slow down the high-energy neutrons produced during a nuclear fission reaction. Slowing down the neutrons increases the likelihood of their interaction with other fissile nuclei, allowing for sustained and controlled nuclear reactions.
In the absence of a moderating material, the high-energy neutrons produced during a nuclear reaction will continue to have high velocities. These fast neutrons are less likely to cause additional fission reactions, leading to an inefficient use of fuel and an uncontrolled chain reaction. The lack of moderation can result in a rapid release of energy, known as a nuclear explosion or a runaway reaction, which can be highly destructive and dangerous.
Therefore, the presence of a moderating material is crucial to maintain a controlled and sustained nuclear reaction in applications such as nuclear power generation or research reactors.